This invention relates to devices used in vehicular internal combustion engines to provide efficient control and use of the crankcase fumes.
It has been known that automobile engines contribute to atmospheric pollution by spewing forth unburned and partially burned gaseous hydrocarbons and even droplets of unburned oil. A principal offender in this respect are the fumes which originate in the crankcase and which in the past were allowed to escape to the atmosphere. In recent times laws have been passed which require the fumes to be channeled back to the air intake manifold of the engine, there to be mixed to the incoming fuel-air mixture so that the unburned hydrocarbons in the fumes will be burned in the engine cylinders.
In existing automobile engines, a crankcase ventilation conduit has its intake end usually located upstream of the carburetor in such manner as to pass fresh air into the crankcase. Ventilation of the crankcase is achieved by drawing off this air and entrained fumes, gases, etc., through a conduit connected to the downstream side of the carburetor or to the air intake manifold. The crankcase fumes and ventilating air pass into the induction system downstream of the carburetor. Because of this, the flow from the crankcase to the intake manifold must be controlled. To provide such control, a pollution control valve or positive crankcase ventilation valve(PCV valve) is located in the conduit connecting the crankcase to the engine air intake manifold. The PCV valve closes during engine idling when the vacuum in the intake manifold is high. When the PCV valve is closed, the ventilated air and fumes either are blocked off entirely or only small amounts are allowed to pass through an orifice in the PCV valve.
As the engine speeds up, the PCV valve opens to permit larger quantities of air and crankcase fumes to be drawn into the intake manifold, thus increasing the ventilation effect in the crankcase. The PCV valve operates in a puttering manner, rather than smoothly fully opening and closing. While the PCV valve is quite effective in obtaining less ventilation when the engine is idling and more ventilation when the engine is speeded up, the minimal flow through the PCV valve during idling adversely affects engine idling and increases gasoline consumption. The design of the PCV valve is a compromise between good idling and effective burning of the crankcase fumes.
In engines which are not provided with a PCV valve it is still desirable to increase the air flow into the intake manifold downstream of the carburetor, except when the vehicle is idling and the intake manifold vacuum is high. An additional supply of air reduces the amount of vaporized fuel which is drawn through the carburetor and that would be wasted in the vehicle exhaust and would pollute the environment. The richness of the fuel air mixture is preferably reduced. A more correct air-to-fuel ration is assured.
In a vehicle having a PCV valve, the device of the present invention is designed for being positioned in the conduit leading from the PCV valve to downstream side or base of the carburetor. The device acts to permit improved idling characteristics and reduced fuel consumption. In a vehicle engine that pipes crankcase fumes through a PCV valve back to the intake manifold, often there is insufficient oxygen for complete combustion of the gasoline plus the unburned combustible hydrocarbons in the crankcase fumes. The device of the invention helps supply that needed oxygen and also breaks up the unburned hydrocarbons to facilitate their combustion. There are many devices which attempt to solve this problem. Such devices of this general type are disclosed in U.S. Pat. No. 3,809,035; U.S. Pat. No. 3,923,024; and in the previous patents of Juanita Norman U.S. Pat. Nos. 4,183,336 and 4,305,369.
In each of these prior art devices there is a means for opening a passageway to permit ambient air to enter the fuel-air mixture leaving the carburetor under selected low speed conditions and also to suddenly admit large amounts of such air. There has been no attempt in the past to provide a device which will gradually admit more and more ambient air as the speed of the engine is increased, and to reduce that ambient air at still higher speeds. The optimum operation of the device of the present invention is to provide no ambient air at idling conditions and to increase the amount of ambient air as the vehicle speed is increased to about 88 km./hr. and thereafter to decrease the amount of ambient air as the speed is increased to about 113 km./hr. until the ambient air is shut off completely and remains in that condition at still higher speeds. Accordingly it is an object of this invention to provide an improved fuel-air control device. It is still another object of this invention to provide an improved fuel-air control device that provides the optimum amount of ambient air at different speeds of the engine. It is still another object of this invention to provide such a device that is mechanically operated and does not rely upon electronic sensing. Yet another object is to obtain lower exhaust emissions of pollutants from the engine. Still other objects will be apparent from the more detailed description of this invention which follows.